<!DOCTYPE html>
<html lang="en" xmlns:v-bind="http://www.w3.org/1999/xhtml">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    *.active {
      color: red;
    }

    *.underLine {
      text-decoration: underline;
    }
  </style>
</head>
<body>

<div id="app">
  <h2 v-bind:class="['active','underLine']">{{message}}</h2>
</div>

<script src="../js/vue.js"></script>
<script>
  const app = new Vue({
    el: '#app',
    data: {
      message: 'Rae是我儿子！'
    }
  })
</script>

</body>
</html>